Kolmijako

/**
 * Datatähti 2021 loppu
 * 358
 * B
 * Kolmijako
 * @author TRS
 */
//Include
#include <bits/stdc++.h>
//Definitions
using namespace std;
//Constants
#define infinity 0x3f3f3f3f
#define linfinity 0x3f3f3f3f3f3f3f3f
#define MOD 1000000007
int n;
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    cin>>n;
    if ((n * (n + 1) / 2) % 3 != 0) {
        cout<<"IMPOSSIBLE"<<"\n";
        return 0;
    }
	if (n == 3) {
	    cout<<"1 2 3";
	    return 0;
    }
	if (n == 5) {
        cout<<"1 3 1 3 2";
        return 0;
    }
	if (n == 6) {
        cout<<"2 1 3 1 3 2";
        return 0;
    }
	int k = (n + 2) / 3;
	int results[k * 3];
	if (k % 2 == 0) {
		results[0] = 2;
		results[1] = 1;
		results[2] = 3;
		results[3] = 1;
		results[4] = 3;
		results[5] = 2;
		for (int i = 6; i < k * 3; i++) {
			if (i % 6 == 0) {
                results[i] = 1;
			}
			if (i % 6 == 1) {
                results[i] = 2;
			}
			if (i % 6 == 2) {
                results[i] = 3;
			}
			if (i % 6 == 3) {
                results[i] = 3;
			}
			if (i % 6 == 4) {
                results[i] = 2;
			}
			if (i % 6 == 5) {
                results[i] = 1;
			}
		}
	}
	else {
		results[0] = 1;
		results[1] = 2;
		results[2] = 3;
		for (int i = 3; i < k * 3; i++) {
			if ((i - 3) % 6 == 0) {
                results[i] = 1;
			}
			if ((i - 3) % 6 == 1) {
                results[i] = 2;
			}
			if ((i - 3) % 6 == 2) {
                results[i] = 3;
			}
			if ((i - 3) % 6 == 3) {
                results[i] = 3;
			}
			if ((i - 3) % 6 == 4) {
                results[i] = 2;
			}
			if ((i - 3) % 6 == 5) {
                results[i] = 1;
			}
		}
	}
	for (int i = k * 3 - n; i < k * 3; i++) {
		cout<<results[i]<<" ";
	}
    return 0;
}

Test 1

Group: 1, 2

Verdict: ACCEPTED

Test 2

Group: 1, 2

Verdict: ACCEPTED

Test 3

Group: 1, 2

Verdict: ACCEPTED

Test 4

Group: 1, 2

Verdict: ACCEPTED

Test 5

Group: 1, 2

Verdict: ACCEPTED

Test 6

Group: 1, 2

Verdict: ACCEPTED

Test 7

Group: 1, 2

Verdict: ACCEPTED

Test 8

Group: 1, 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: ACCEPTED

Test 10

Group: 2

Verdict: ACCEPTED

Test 11

Group: 2

Verdict: ACCEPTED

Test 12

Group: 2

Verdict: ACCEPTED

Test 13

Group: 2

Verdict: ACCEPTED

Test 14

Group: 2

Verdict: ACCEPTED

Test 15

Group: 2

Verdict: ACCEPTED